battery removal thought experiment

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nerd king

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Hi folks,
I'm planning a long cross-country loop and can either take my Clarity PHEV which would be just dandy except for the only 40 or so mpg and no real practical on the go charging solutions, or I can purchase a different efficient vehicle for the trip (and keep as a work and long trip vehicle after). Then I got to thinking what would the MPG effect be on removing the traction battery and replacing it with a much lighter pack at the same voltage? My target capacity would be equivalent to the charge at the minimum reserve state that happens when the car runs low on charge and the engine fires up. The big hurdles would be the PITA of removing the battery, and the cost of assembling a new voltage equivalent one. Could this be done without freaking out the battery management systems? I doubt this is something I would ever attempt, especially with a newer vehicle under warranty and in good shape, but in ten years? who knows? The thought of losing 6-700 lbs of battery that I would be driving around for 5000 miles is appealing. I wonder what effect that kind of weight reduction would have on gas only mpg? Any guesses?
 
40+ mpg is pretty good. If you're trying to save money i doubt if any other solution would be better than just driving it and keeping the battery charge about 50%
 
If you obtain the estimated 47 mpg, fuel consumption for the entire trip will be reduced by ~20 gallons compared to an unmolested, under warranty Clarity, at 40 mpg. That would reduce fuel costs by ~$50.

Have you estimated the cost of the proposed project or the price of a different efficient vehicle?

What route are you planning that offers no charging options? Seattle to Fairbanks?

The Clarity has an actual on the go charging option. It’s called HV Charge and will charge the traction battery up to ~60% while driving. If you start the trip with a fully charged battery, and drive in HV mode, you may not need to charge the battery for the entire trip.
 
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Landshark said:
If you obtain the estimated 47 mpg, fuel consumption for the entire trip will be reduced by ~20 gallons compared to an unmolested, under warranty Clarity, at 40 mpg. That would reduce fuel costs by ~$50.

Have you estimated the cost of the proposed project or the price of a different efficient vehicle?

What route are you planning that offers no charging options? Seattle to Fairbanks?

The Clarity has an actual on the go charging option. It’s called HV Charge and will charge the traction battery up to ~60% while driving. If you start the trip with a fully charged battery, and drive in HV mode, you may not need to charge the battery for the entire trip.
Click to expand...
Seattle to Fairbanks has charging options.
 
Landshark said:
If you obtain the estimated 47 mpg, fuel consumption for the entire trip will be reduced by ~20 gallons compared to an unmolested, under warranty Clarity, at 40 mpg. That would reduce fuel costs by ~$50.

Have you estimated the cost of the proposed project or the price of a different efficient vehicle?

What route are you planning that offers no charging options? Seattle to Fairbanks?

The Clarity has an actual on the go charging option. It’s called HV Charge and will charge the traction battery up to ~60% while driving. If you start the trip with a fully charged battery, and drive in HV mode, you may not need to charge the battery for the entire trip.
Click to expand...
 
I realize it wouldn't be a cost effective solution, just a thought experiment, to wrap my head around unusable weight vs fuel economy. And by no charging options I meant that for me a level 2 charger isn't really practical for a quick fill up and moving back on down the road. This would be a Maine to Texas up to California up to Alaska and back through Canada kind of journey. Charging where I could of course, longer stops and overnight at hotels if possible. The HV charge just uses gas to charge the battery so reduces fuel economy and seems sort of pointless from that perspective. I think the option was offered for preparing to enter future urban exclusion zones where only EV power is allowed. If you found yourself low on charge you could charge a bit on the way to prepare.
 
And don't get me wrong, I love my car, a 2018 Moonlit Forest Pearl Base. It's perfect for most everything I need except this long slog I'm thinking about doing. And really it's fine for that too, just not optimal, but every car can't do every scenario perfectly, and the Clarity strikes a good balance. Probably will end up taking it and plan lunch breaks around charging stops and get an hour in while I dine and walk around..
 
nerd king said:
And by no charging options I meant that for me a level 2 charger isn't really practical for a quick fill up and moving back on down the road.
Click to expand...

Driving in HV does not significantly deplete the battery. I’ve driven 700 miles in a day and seen the battery gauge drop just 2-3 bars. An overnight charge, at a hotel, on L1 will fully charge the batteries. Or an hour or 2 of L2 charging while out for dinner would charge them up as well. There is no need to charge the battery when getting fuel or having lunch.

nerd king said:
The HV charge just uses gas to charge the battery so reduces fuel economy and seems sort of pointless from that perspective.
Click to expand...

A couple of members have reported using HV Charge exclusively, while getting 52mpg. I agree there have to be losses and it can’t be 100% efficient, but I haven’t used it enough reach a conclusion.

There have also been many recommendations to keep the battery above the minimum SOC for better overall performance. Your idea of replacing the 17kWh battery with a 3-4kWh battery might be a recipe for a very unpleasant driving experience.
 
If you do take the Clarity on this trip (I would highly recommend it), then I fail to understand your apparent desire to "charge where you could". The only reason I would even consider charging on an extended trip would be if you happened upon a convenient free charging setup. If you have to pay for charging, then it is almost a certainty that the electric cost in this scenario would exceed the equivalent cost of gasoline.

I would take the clarity, and not think twice about making the trip exclusively gas. I would operate entirely in HV mode with ~50% SOC. Your SOC will inevitably trail off either due to terrain, or you will forget to engage HV ever time you start. Just use HV Charge occasionally (as needed) to boost yourself back up to ~50% range. No worries, and no need to even think about charging along the way.

You may even find that you are getting more than 40 MPG for a large portions of your trip...
 
I took my car on road trip from CT thru PA to Ohio and then on the way back up through Niagara Falls, around 2000 miles. Charged every night on L1 at hotels. In the morning I'd use EV until SOC bars were about 70% and then HV rest of the way until was close to my destination then ran EV down to 0. Great driving experience (quiet ICE), room for regen and no fear of running out of either fuel. I averaged around 60-65mpg IIRC when including the free juice when driving around 3-400 miles a day.

Not worth the hassle to remove the battery to save a few bucks in fuel IMO

EDIT I would love to see the real world effects of HV charge to see impact to overall mileage in different driving scenarios (mixed, all highway, hills etc)
 
MrFixit said:
If you do take the Clarity on this trip (I would highly recommend it), then I fail to understand your apparent desire to "charge where you could". The only reason I would even consider charging on an extended trip would be if you happened upon a convenient free charging setup. If you have to pay for charging, then it is almost a certainty that the electric cost in this scenario would exceed the equivalent cost of gasoline.

I would take the clarity, and not think twice about making the trip exclusively gas. I would operate entirely in HV mode with ~50% SOC. Your SOC will inevitably trail off either due to terrain, or you will forget to engage HV ever time you start. Just use HV Charge occasionally (as needed) to boost yourself back up to ~50% range. No worries, and no need to even think about charging along the way.

You may even find that you are getting more than 40 MPG for a large portions of your trip...
Click to expand...

My desire to charge where I can is based on the fact that electricity is a cleaner source of power than gasoline. It would reduce my overall carbon emissions for the trip. I agree that I wouldn't save any money by seeking out and paying for chargers
 
nerd king said:
electricity is a cleaner source of power than gasoline
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That is a loaded question, and I don't want to start a firestorm.
Suffice to say that electricity is only as clean as the ultimate source.
There will be some places that you go through across the country where the electricity is not so "clean" and other places where it is.

All-in-all, I doubt that you could substantially reduce your carbon footprint. That's a whole lot of miles and your EV usage will be a pretty small percentage try as you may.
 
Landshark said:
Driving in HV does not significantly deplete the battery. I’ve driven 700 miles in a day and seen the battery gauge drop just 2-3 bars. An overnight charge, at a hotel, on L1 will fully charge the batteries. Or an hour or 2 of L2 charging while out for dinner would charge them up as well. There is no need to charge the battery when getting fuel or having lunch.



A couple of members have reported using HV Charge exclusively, while getting 52mpg. I agree there have to be losses and it can’t be 100% efficient, but I haven’t used it enough reach a conclusion.

There have also been many recommendations to keep the battery above the minimum SOC for better overall performance. Your idea of replacing the 17kWh battery with a 3-4kWh battery might be a recipe for a very unpleasant driving experience.
Click to expand...

If it takes 2 hours to fully charge the pack, an hour of charging at lunch would give around 75% SOC. Why pass it up if it's there? Charging during dinner is ok but not during lunch? And I find that driving at the minimum SOC works fine in my vehicle, I haven't experienced the "angry bees" effect, just an occasional higher than normal idle at low speeds which is fine. Maybe the ECU has adapted to my driving style, or if the programming is slightly different in the cars that get the angry bees engine sound.
 
The question no one has asked is why do you get such poor gas mpg on your car? I haven't gotten worse than 48 in the last 3 months (drive 100% on gas so lots of data) , do you drive over 80 mph? The only time I hit 40 (and lower) is in winter.
 
nerd king said:
Charging during dinner is ok but not during lunch?
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I suggested charging at dinner as that might be at a time of day when you had completed your driving and settled in to a hotel. The car is parked, plug it in. Depleting and recharging the batteries multiple times on a single trip is not something I would ever do. For any reason.
 
David Towle said:
I haven't gotten worse than 48 in the last 3 months (drive 100% on gas so lots of data) , do you drive over 80 mph?
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I realize that I was not asked this question. However, I have made several long trips at mostly 75-80mph in HV. The computer showed just under 40mpg. Actually mpg was closer to 36.

Local trips are made almost entirely in EV, so I have no idea what the fuel consumption would be while driving in HV around town or at slower speeds.
 
I've gotten mid 40's, maybe even upper 40's, but have to drive closer to 50-60 mph to attain that. From my experience, driving 75-80 in HV yields pretty much exactly what @Landshark quoted. Still, I am impressed with the efficiency. I average about 65% electric, so the mpg isn't all important to me.
 
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